So why didnt Microsoft build Vista on .NET?
This looks like the answer from anadk's link, and i almost agree with it.
The problem, it turns out, is that the .NET builders did not give much thought to providing many of the essential basic building blocks that operating systems construction crews need for their work. Interpreted code has some minor performance issues as well (note that there are many ways to overcome this often overly shrill critique). But the main problem was that the Microsoft OS guys are big C++ users. Getting them to switch over to C# was for these reasons not in the cards.
By the way, Microsoft is working on such an OS to incorporate a language, maybe better than .Net, and its called
Singularity. I quote a few words from MS on it here:
Singularity is a research project focused on the construction of dependable systems through innovation in the areas of systems, languages, and tools. We are building a research operating system prototype (called Singularity), extending programming languages, and developing new techniques and tools for specifying and verifying program behavior.
Advances in languages, compilers, and tools open the possibility of significantly improving software. For example, Singularity uses type-safe languages and an abstract instruction set to enable what we call Software Isolated Processes (SIPs)...
From what I have come to think of, these things may well be incorporated in "Vienna", that is going to change the way we use computers (of course, that's as per BG & MS - only time will tell).
